Ultrasonically vibrated cutting knives



lApril 23, 1963 BALAMUTH ETAL 3,086,288

ULTRAsoNIcALLY VIBRATED CUTTING KNIVES Filed April 20, 1955 United States Patent O 3,086,288 ULTRASQNCALLY VHBRATED CUTTHNG KNIVES Lewis Balamuth, Sunnyside, and Arthur Kurtis, Bronx,

N.Y., assignors to Cavitron Ultrasonics, Inc., a corporation of New York Filed Apr. 20, 1955, Ser. No. 562,672 8 Claims. ((Il. :ttl- 272) The present invention relates to high frequency vibrated cutting tools and more particularly to an ultrasonically vibrated cutting knife which cleanly and rapidly cuts tough materials such as hard rubber, wood, leather, or the like, materials that soften or melt when heated, such as thermoplastic resins and frozen products, and fibrous or sinewy materials such as human or animal esh and bone. The new cutting tool requires application of but a small amount of pressure by the operator, essentially only that suliicient for guidance of the knife edge in the desired direction of cut.

The new tool comprises an edged blade into which are injected longitudinal vibrations `of ultrasonic frequency and fof small amplitude from an electromechanical transducer contained Within a hand piece and coupled through flexible tubing to a remote source of electrical oscillations. The hand piece may be, and preferably is, of the general construction of the hand piece of an ultrasonic dental instrument recently introduced into commercial use for application to dental cavity preparation. The blade is provided with a sharp cutting edge and preferably also with a sharp pointed tip. At the end of the blade remote from the tip the blade is provided with means for a-ttachment to the driving element within the hand piece.

The new tool is particularly designed for use as a surgical instrument for cutting of bone and flesh. For such application a relatively yshort blade is preferred by the ysurgical profession. With such a short blade the length thereof is small compared to the wavelength of sound in the material of the driving unit and of the blade at the `operating frequency, which is ordinarily in the neighborhood of 30 kc. per second. Under these conditions, with the overall length of the tool such as to yield a loop of motion at or near the tip of the blade the amplitude of vibration does not vary appreciably over the length of the edged portion of the blade.

ln use, with the blade vibrating as a result of the longitudinal vibrations injected therein from 'the driving element, an operator handles the tool as he would an ordinary knife except that much less pressure is applied in the cutting operation. Because of the extreme ease with which the vibrating blade cuts through material-s of the type previously identified, it does not introduce tensile strain in the material prior to penetration and therefore minimizes the danger of tearing incident to cutting of esh, for example, when substantial pressure is required for making the first penetration of the skin. Thus a clean cut at the exact location desired is achieved in use of the new tool.

Another feature of the vibrating blade is the heat generated thereby. In certain cutting operations this feature is of substantial value. In other operations, localized heating during cutting is of no particular advantage and in such case cooling fluid can be applied to the cutting area. When thermoplastic resins or parain are to be cut the vibrating blade of the invention is highly effective as compared with knives heretofore used for cutting such substances. When materials such as these are cut by the new vibrating blade the material appears to melt ahead of the blade and to rise up on either side and clean itself out from the cut being formed. The jamming which results when the conventional type of knife is employed for cutting heat softening materials is thus entirely eliminated when the vibra-ting knife of the present 3,0%,288 Patented Apr. 23, 1963 M invention is used. Also, the self-cleaning action above described with reference to the cavity or slot `in a heat softening material applies also to `the blade itself. When a heat softening and adhesive material is cut with the vibrating blade no adhesive substance adheres to the blade in counter-distinction to the accumulation on the blade of cut material when conventional knives are employed.

The self-cleaning action observed when -heat softening materials are cut with the vibrating knife is believed to be due to local velocity gradients set up in the knife as a result of the high frequency longitudinal vibrations therein. The relatively slower moving molten material appears to be continually urged from one position to another by the rapid particle vibration of the material of the blade before being thrown off from the blade on to the uncut surface of the work where -it accumulates and solidilies.

So far as rapidity of cutting is concerned the rate at which materials are cut with the vibrating blade of the invention is vastly higher than that approachable with conventional knives. This feature is of immense value to surgeons for reducing the period of time during which a patient is subjected to the knife with or without anesthesia. The new knife is particularly suitable, for example, for use in lobotomy wherein circular `or other sections of the human skull have to be removed. The new tool rapidly and directly cuts out the required section. The practice heretofore in use is time consuming and an ordeal to the patient as it involves preliminary drilling of a number of separate holes followed by cutting of interconnections between holes.

As .heretofore indicated, the hand piece of the new tool may be constructed substantially like the hand piece of the ultrasonic dental equipment now in commercial use. It is advantageous, particularly if the new vibrating knife is to be used by dental surgeons, to so dimension the knife and the means thereon for attachment to the driving unit, that it may be attached directly to the ultrasonic dental hand piece in place of the tool bit of that equipment. Thus a dentist equipped with the ultrasonic drilling equipment could readily employ his :apparatus for surgical work, disconnecting the means thereof for supplying yan abrasive slurry to the Work area or utilizing such means for delivery of cooling fluid.

For a better understanding of the invention `and of specific embodiments thereof, reference may be had to the accompanying drawings of which;

FIG. l is `a longt-iudinal section through a high frequency vibrated cutting tool embodying the invention;

FIG. 2 comprises two diagrams, a and b, comparing the tearing action .of a conventional knife with the nontearing action of a high frequency vibrated cutting knife such :as that shown in FIG. l, when cutting certain types of material;

FIG. 3 illustrates the self-cleaning laction when heat softening materials are cut with a high frequency vibrated knife such `as that shown in FIG. l; `and FIGS. 4, 5 and 6 illustrate different shapes `of knife blades sui-table for use in the new tool.

The high frequency vibrated cutting tool illustrated in FIG. l comprises a casing 2 of cylindrical cross section of `a size convenient for manipulation by an operator. A length 2a of the casing at one end thereof may be of relatively small diameter and open ended. A length 2b at the other end of the casing may be of substantially larger cross section and internally threaded at its end. A cent-rally apertured cap 4 is threaded to the larger end 2b of the casing. The two end sections of different diameters are connected by a section 2c of intermediate diameter and of `a length Iapproximately equal to that of the end section 2a. Preferably the outer surface of the casing is covered with a layer 6 of vibration absorbing material, such as rubber having closed air cells therein. Within the section 2b of the easing is a magnetostrictive transducer comprising a laminated stack 8 of nickel or other magnetostrictive material and an yenergizing winding 10 therefor. One end of the stack is weldedl yor soldered to an end of a tool holder 12 shaped to serve as an acoustical impedance transformer. The holder =12 extends through sections 2c and 2a of the casing and comprises twocylinders of different diameters interconnected by a short tapered section 12a. The overall length of the tool holder or transformer 12 is substantially equal to one-half wavelength of standing waves set up therein at the `operating -frequency of the equipment, land the junction of the sections of different diameters occurs substantially Iat the node of motion of such standing waves. Magnification of amplitude of vibration is attained by virtue of a mass effect as described in the copending application of Lewis Balamuth and Arthur Kuris, Serial No. 417,407, entitled Vi-bratory Machine Tool, filed March 19, `1954, and now Patent Re. 25,033. -It is at this nodal region that the transformer, with the transducer secured thereto, is mounted within the casing 2 of the hand piece. The mounting means comprises Ia ring y14 of compressible material, such as rubber, which seats in an annular recess in the tool holder or transformer 12 and forms a yielding watertight coupling between the casing 2 'and the transformer contained therein. The compressible ring 14 does not appreciably dampen radial vibrations at the nodal region of the transformer and therefore does not subject the transformer to external stresses. To prevent relative rotation between the holder and the casing a transverse pin 16 is mounted in aligned transverse passages in the casing and holder adjacent the nodal region 12a. The holder i12 is provided at its end with an axial threaded aperture for reception of a threaded stud 18 formed on the end of a short th-in knife 20.

A plug 22 which is held by friction within section 2b of the casing 2 and abuts the cap 4 is provided with three apertures therethrough. These apertures are for `accommodation of water inlet and outlet hoses 24 and 26, respectively and for a coaxial electrical cable 28. The coaxial cable 28 comprises an outer metallic grounded cover which is conductively connected to the casing 2 through the plug 22 and yan inner conductor provided with lan insulating water impervious coating. The insulated inner conductor forms the winding 10 and is grounded at its end to the stack 8 or to the casing 2. The diameter of the casing 2 is such that there is only small play between the transducer stack 8 and the inner wall of the casing. Thus the transducer and tool holder are centered without 'having added any ycomponents which could hamper vibration. Extending along the inner wall of section 2b of the casing and adjacent the transducer stack 8 yis a water delivery line 32 which at one end is connected within the plug 22 to the water inlet hose 24 :and terminates lat its other end adjacent the junction of the stack with the transformer. A short water outlet conduit 34 is connected in the plug 22 to the outlet hose 26.

The two hose connections 24 and 26 and the cable Z8 extend through the aperture in cap 4 and beyond the cap are confined within a spiral spring 36 serving as a flexible sheath for the hose connections and cable. It will be understood that a suitable source of high frequency electrical oscillations and of D.C. bias current will be coupled through the cable 28 to the transducer winding 10` and that the hoses 24 and 26 will be connected to suitable water supply and drain lines (not shown).

The knife comprises a generally hexagonal shaped base 38 with which the threaded stud 18 is formed integral and a thin straight blade 40 having a knife edge 42 `along one side thereof. When the length of the knife 20 is small compared to the wavelength of sound waves in the materials of the transducer, tool holder and knife at the operating frequency, and when the ratio of the cross Sectional area of the blade to that of the adjacent end of the tool holder is small, the amplitude of vibration will not vary substantially along the blade. A loop of motion of the standing waves set up in the tool holder at the operating frequency exists at the free end of the tool holder before attachment of the knife. After the knife is mounted on the tool holder a loop of motion exists at the tip of the knife, with or without a small shift in the operating frequency depending upon the length of blade and the cross section thereof. With knives of relatively short length and small cross section the change in operating frequency is practically negligible and the amplitude of vibration over the length of the knife edged portion is practically constant. With blades of one-fourth wavelength or less and cross sectional area of one-fifth that of the adjacent end of the tool holder, the amplitude of vibration along the knife will not vary by more than 20%.

The knife of FIG. 1 is pointed and the blade thereof is relatively straight. When vibrated as the result of injection of longitudinal vibrations of the order of 30 kc. it will rapidly and effectively cut tough materials, heat softening materials and fibrous or sinewy materials. Only slight pressure is required for .initial penetration and continued cutting of such materials. When used for cutting flesh, for example, this feature is of particular value in avoiding a tearing action.

When a conventional non-vibrating knife blade, irrespective of how sharp it may be, is used to cut flesh or material similar thereto, the flesh is first compressed before actual penetration occurs. This is indicated diagrammatically in FIG. 2 at a wherein the reference numeral 44 represents human or animal flesh and the reference numeral 46 indicates the outer surface or skin thereof. A conventional knife blade 48 is shown in section and on a greatly enlarged scale. When such type of knife is employed the skin 46 which was initially in the position indicated by the dotted line 50 will be forced downwardly by the blade 48 before penetration occurs. When pressed downwardly to the full line position of the skin 46 pulling forces are set up in the skin as indicated at 52. Consequently, upon penetration of the skin tearing action results. As compared to such tearing action resulting from the use of a conventional knife, the vibrating knife of the present invention will penetrate the skin practically upon Contact. This is illustrated diagrammatically in FIG. 2 at b wherein the cross section of the blade 4) of the knife of FIG. l is shown in greatly enlarged scale. Penetration is initiated without depression of the skin 46 of the flesh.

FIG. 3 illustrates the self-cleaning effect that results when a vibrating knife such as that of FIG. l is employed to cut heat softening materials such as a thermoplastic resin. In FIG. 3 a cylinder of thermoplastic resin is indicated at 54. The vibrating blade 40 of the knife of FIG. l is shown in the process of cutting the cylinder 54. The heat generated by the rapidly vibrating edge of the blade fuses the resin in advance of the cutting edge of the blade. The liquified resin thereupon flows up along the sides of the blade and bubbles out upon the surface of the plastic rod as indicated at 56 thus permitting rapid cleaning and easy cutting of the resin. None of the liquid resin deposits upon the blade because of the rapid vibration thereof.

The shape of blade and the location of the cutting edge thereof will depend in large part upon the particular use to which the knife is to be put. A sharp tip such as that shown on the blade of the knife of FIG. l is ordinarily desirable for initial penetration of -material to be cut.

In FIGS. 4, 5 and `6 knives of different configuration and suitable for use as the cutting tool of the invention are illustrated. In FIG. 4 the knife comprises an arcuate blade 58 having a cutting edge 60` along the concave side thereof and a hexagonal base `62 provided with a threaded stud 64 for attachment to the tool holder. In FIG. 5 a

knife having a relatively wide blade 66 provided with a knife edge `68 along the convex side thereof is illustrated. The blade 70 of the knife of FIG. 6 is provided with knife edges '72 and 74 along opposite sides thereof which knife edges merge into the sharp point '76 of the relatively triangular shaped blade.

Each of the knives illustrated in the drawing is suitable for use by surgeons. Other configurations and other dimensions of knife could as well be employed.

The invention has now been described with reference to various embodiments. From the foregoing description it will be apparent that the invention comprises a manually manipulated tool whose handpiece casing 2 does not vibrate or reciprocate, but whose knife edged blade reciprocates relative to the handpiece casing as a result of the longitudinal vibrations of high frequency which are injected into the knife blade, so that the knife edge is subjected to high frequency vibration of small amplitude but high acceleration; the amplitude being in general under .001" and `the acceleration many times that of gravity. The reason for the rapid and effective cutting made possible by the use of the high frequency vibrated cutting knife of this invention is not fully known. However, in cutting heat softening materials, it is believed the heat generated at the cutting edge during the cutting operation plays an important part in incr-easing the cutting rate, and in cutting bone, flesh and other materials it is believe-d possible that the high acceleration given to the individual minute points making up the cutting edge introduces a rapid sawing action which combined with the relatively small pressure provided by the operatot results in the rapid and effective cutting. Irrespective of any theoretical explanation, it has been demonstrated that highly improved, efficient and surprising cutting results are achieved when high frequency longitudinal vibrations are established along the cutting edge and at .the cutting point of the knife blade in accordance with this invention, and which cannot be attributed to the form or shape of the cu-tting blade itself. Although an operating frequency in the neighborhood of 30 kc. per second has been su-ggested herein, the invention is not limited to the employment of such specific frequency, as higher or lower operating frequencies are entirely practicable.

The following is claimed:

l. An ultrasonically vibrated surgical knife designed to be held in the hand which includes, a tubular handpiece, a Inatgnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular handpiece, an amplitude magnifying acoustical impedance transformer rigidly fixed to one end of sai-d vibrator member and contained within said tubular handpiece, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section having a cutting edge extending from said neck section and beyond the adjacent end of said tubu-lar handpiece, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it its rigidly secured and tapered side faces which merge into the side faces of the blade section of the knife, the cross-Sectional area of the neck section in the region of attachment to said transformer being a plurality of times greater than the cross-sectional area of the blade section, said magnetostrictive vibrator member, impedance transformer and knife fixed Ithereto having a combined length substantially equal to an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass 'with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient sealing element located between the transformer and tubular handpiece at .the approximate nodal area of the transformer and which provides substantially the sole direct contact support for the magnetostrictive Vibrator, impedance transformer and cutting knife, -a sealing plug extending into said tubular handpiece and spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element cooling chamber therebetween, bias current conductors extending through said sealing plug and connected to said winding, and inlet and outlet tubes extending through said sealing plug for supplying a coolant to said chamber and withdrawing coolant therefrom.

2. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an amplitude magnifying acoustical impedance transformer rigidly fixed to one end of said vibrator member, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a cutting edge extending from said neck section and beyond the adjacent end of said tubular holder, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it is rigidly secured and tapered side faces which merge into the side faces of the blade section of the knife, the cross-sectional area of the neck section in the region of attachment to said transformer being a plurality of times greater than the cross-sectional area of the blade section, said magnetostrictive vibrator member having a length substantially equal to a half wavelength or an integral number of half wavelengths at the frequency of operation of the blade section of the knife and said impedance ltransformer and knife fixed thereto having a combined length substantially equal to a half wavelength or an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substanti-ally at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient sealing element located between the transformer and tubular handpiece at the approximate nod-al area of the transformer and which provides substantially the sole direct contact support for the magnetostrictive vibrator, impedance transformer and cutting knife without material dampening of the radial vibrations of the transformer, a sealing plug extending into said tubular holder and spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling 4chamber therebetween, bias current conductors extending through said sealing plug and connected to said winding, an inlet tube extending through said sealing plug for supplying coolant to said chamber, and an outlet tube extending through said sealing plug for withdrawing coolant from said chamber.

3. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a lrnagnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an acoustical impedance transformer rigidly fixed to one end of said vibrator member and contained within said tubular holder and having a vibration magnifying action due at least in part to a -rnass effect, .a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a curved cutting edge and a sharp point extending from said neck section and beyond the adjacent end of said tubular holder, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it is rigidly secured and tapered side faces which merge into the side faces of the blade section of the knife, the cross-sectional area of the neck section in the region of attachment to said transformer being a plurality of times greater than the cross-sectional area of the blade section, said magnetostrictive vibrator member, impedance transformer and knife fixed thereto having a combined length substantially equal to an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient sealing element located between the transformer and tubular handpiece at the approximate nodal area of the transformer and which provides substantially the sole direct contact support for the magnetostrictive vibrator, impedance transformer and cutting knife without material dampening of the radial vibrations of the transformer, a sealing plug extending into said tubular holder and spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, a tiexible conduit extending from said sealing plug, bias current conductors in said flexible conduit extending through said sealing plug and connected to said winding, and inlet and outlet tubes in said conduit land extending through said sealing plug for supplying a coolant to said chamber and withdrawing coolant therefrom.

4. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an acoustical impedance transformer rigidly fixed to one end of said vibrator member and contained within said tubular holder, al cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a cutting edge terminating in a sharp point extending from said neck section and beyond the adjacent end of said tubular holder, the neck section of said cutting knife having a cross-sectional area in the region of attachment to said transformer which s a plurality of times greater than the cross-sectional area of the blade section and having tapered side faces which merge into the side faces of the blade section of the knife, said magnetostrictive vibrator member, transformer and knife fixed thereto having a combined length substantially equal to an integral multiple number of half wavelengths at the yfrequency of operation of the blade section of the knife, the cutting edge of said blade section having a length which is less than a quarter wavelength at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient vibration absorbing sealing element located between the transformer and tubular holder at the approximate nodal area of the transformer which provides substantially the sole direct contact support for the magnetostrictive vibrator member, impedance transformer and cutting knife, an end closure for said tubular holder spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, bias alternating current conductors extending through said end closures and connected to said winding, and inlet and outlet tubes extending through said end closure for circulating a coolant through said chamber.

5. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an amplitude magnifying acoustical impedance transformer rigidly fixed to one end of said vibrator member and contained within said tubular holder, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a curved cutting edge and a sharp point extending from said neck section and beyond the adjacent end of said tubular holder, the neck section of said cutting knife having a cross-sectional area in the region of attachment to said transformer which is a plurality of times greater than the cross-sectional area of the blade section and having tapered side faces which merge into the side faces of the blade section of the knife, said magnetostrictive vibrator member, impedance transformer and knife fixed thereto having a combined length substantially equal to an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife, the cutting edge of said blade section having a length which is less than a quarter Wavelength at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantial-ly different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient sealing element located between the transformer and tubular holder at the approximate nodal area of the transformer which provides substantially the sole direct contact support for the magnetostrictive vibrator member, impedance transformer and cutting knife, an end closure for said tubular holder spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, bias alternating current conductors connected to said winding and extending through said end closure, and coolant tubes extending through said end closure for supplying coolant to said chamber and withdrawing coolant therefrom.

6. An ultrasonically vibrated cutting lknife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an amplitude magnifying acoustical impedance transformer rigidly xed to one end of said vibrator member and contained within said tubular holder, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a cutting edge and a sharp point extending from said neck section and -beyond the adjacent end of said tubular holder, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it is rigidly secured and tapered side faces which merge into the side faces of the blade section of the knife, the cross-sectional area of the neck section in the region of attachment to said transformer being a plurality of times greater than the crosssectional area of the blade section, said magnetostrictive vibrator member having a length substantially equal to a half wavelength or an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife and said impedance transformer and knife fixed thereto having a length substantially equal to a half wavelength or an integral multiple number of half wavelengths at the yfrequency of operation of the blade section of the knife, and the cutting edge of said blade section having a length which is less than a quarter wavelength at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative aoaaaea to increase the amplitude of vibration delivered to the blade section of the knife, a resilient and vibration absorbing sealing element located between the transformer and tubular holder at the approximate nodal area of the transformer which provides substantially the sole direct contact support for the magnetostrictive vibrator member, impedance transformer and cutting knife without material dampening of the radial vibrations of the transformer, a sealing plug extending into said tubular holder and `spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, bias alternating current conductors extending through said sealing plug and connected to said Winding, Vand inlet and outlet tubes extending through said sealing plug for supplying a coolant to said chamber and withdrawing coolant therefrom.

7. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding `surrounding a mangetostrictive vibrator member contained within said tubular holder, an amplitude magnifying acoustical impedance transformer rigidly fixed to one end of said vibrator member and contained within said tubular holder, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a cutting edge and a sharp point extending from said neck section and beyond the adjacent end of said tubular holder, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it is rigidly secured and tapered side faces which merge into the side faces of the blade section of lthe knife, the cross-sectional area of the neck section in the region Iof `attachment to said translformer being a plurality of times greater than the crosssectional area of the blade section, said magnetostrictive vibrator member having a length substantially equal to a half wavelength or an integral multiple number of half wavelengths at the frequency of operation of the blade section of the iknife, said impedance transformer and knife lixed thereto having a combined length substantially equal to a -half wavelength or an integral multiple number of half wavelengths at the frequency of operation in the blade section of the knife, and the cutting edge of said blade section having a length which is less than a quarter wavelength at the frequency .of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered .to the blade section of the knife, a resilient and vibration absorbing sealing element located between the transformer and tubular handpiece at the approximate nodal area of the transformer and which provides substantially the sole direct contact support for the magnetostrictive vibrator, impedance transformer and cutting knife and provides such support without material dampening of the radial vibrations of the transformer, a sealing plug extending into said tubular holder and spaced from the `free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, bias `alternating current conductors extending through said sealing plug and connected to said winding, and inlet and outlet tubes extending through said sealing plug for supplying a coolant to said chamber and withdrawing a coolant therefrom.

8. An ultrasonically vibrated cutting knife designed to be held in the hand which includes, a tubular holder, a magnetostrictive transducer including a bias current winding surrounding a magnetostrictive vibrator member contained within said tubular holder, an acoustical impedance transformer rigidly fixed to one end of said vibrator member and contained within said tubular holder and having a vibration amplitude magnifying action due at least in part to a mass effect, a cutting knife having a tapered neck section rigidly secured to the other end of said impedance transformer and a blade section presenting a curved cutting edge and sharp point extending from said neck section and beyond the adjacent end of said tubular holder, the tapered neck section of said cutting knife having a base area which approximately conforms to the end area of the impedance transformer to which it is rigidly secured and tapered side faces which merge into the side faces of the blade section of the knife, the cross-sectional area of the neck section in the region of attachment to sai-d transformer being a plurality of times greater than the cross-sectional area of the blade section, said magnetostrictive Vibrator member and impedance transformer and knife fixed thereto together having a combined length substantially equal to an integral multiple number of half wavelengths at the frequency of operation of the blade section of the knife and said curv`ed cutting edge of the blade section having a length which is less than a quarter wavelength at the frequency of operation of the blade section of the knife, said impedance transformer comprising two sections of substantially different mass with the junction of said sections located substantially at a nodal area of longitudinal vibration of said transformer and operative to increase the amplitude of vibration delivered to the blade section of the knife, a resilient and vibration absonbing sealing element located between the transformer and tubular handpiece at the approximate nodal area of the transformer and which provides substantially the sole direct contact support for the magnetostrictive vibrator, impedance transformer and cutting knife and which provides such support without material dampening of the radial vibrations of the transformer, a sealing plug extending into said tubular holder and spaced from the free end of said magnetostrictive vibrator member and forming with said sealing element a cooling chamber therebetween, bias alternating current conductors, extending through said sealing plug and connected to said winding, an inlet tube extending through said sealing plug and into said chamber, and an outlet tube extending through said sealing plug for withdrawing coolant from said chamber.

References Cited in the file of this patent UNlTED STATES PATENTS 281,361 Hart July 17, 1883 886,809 Howell May 5, 1908 1,053,005 Brown Feb. 11, 1913 2,651,148 Carwile Sept. 8, 1953 2,714,890 Vang Aug. `9, 1955 2,730,103 Mackta Ian. 10, 1956 2,781,578 Guilfoyle Feb. 19, 1957 

1. AN ULTRASONICALLY VIBRATED SURGICAL KNIFE DESIGNED TO BE HELD IN THE HAND WHICH INCLUDES, A TUBULAR HANDPIECE, A MAGNETOSTRICTIVE TRANSDUCER INCLUDING A BIAS CURRENT WINDING SURROUNDING A MAGNETOSTRICTIVE VIBRATOR MEMBER CONTAINED WITHIN SAID TUBULAR HANDPIECE, AN AMPLITUDE MAGNIFYING ACOUSTICAL IMPEDANCE TRANSFORMER RIGIDLY FIXED TO ONE END OF SAID VIBRATOR MEMBER AND CONTAINED WITHIN SAID TUBULAR HANDPIECE, A CUTTING KNIFE HAVING A TAPERED NECK SECTION RIGIDLY SECURED TO THE OTHER END OF SAID IMPEDANCE TRANSFORMER AND A BLADE SECTION HAVING A CUTTING EDGE EXTENDING FROM SAID NECK SECTION AND BEYOND THE ADJACENT END OF SAID TUBULAR HANDPIECE, THE TAPERED NECK SECTION OF SAID CUTTING KNIFE HAVING A BASE AREA WHICH APPROXIMATELY CONFORMS TO THE END AREA OF THE IMPEDANCE TRANSFORMER TO WHICH IT IS RIGIDLY SECURED AND TAPERED SIDE FACES WHICH MERGE INTO THE SIDE FACES OF THE BLADE SECTION OF THE KNIFE, THE CROSS-SECTIONAL AREA OF THE NECK SECTION IN THE REGION OF ATTACHMENT TO SAID TRANSFORMER BEING A PLURALITY OF TIMES GREATER THAN THE CROSS-SECTIONAL AREA OF THE BLADE SECTION, SAID MAGNETOSTRICTIVE VIBRATOR MEMBER, IMPEDANCE TRANSFORMER AND KNIFE FIXED THERETO HAVING A COMBINED LENGTH SUBSTANTIALLY EQUAL TO AN INTEGRAL MULTIPLE NUMBER OF HALF WAVELENGTHS AT THE FREQUENCY OF OPERATION OF THE BLADE SECTION OF THE KNIFE, SAID IMPEDANCE TRANSFORMER COMPRISING TWO SECTIONS OF SUBSTANTIALLY DIFFERENT MASS WITH THE JUNCTION OF SAID SECTIONS LOCATED SUBSTANTIALLY AT A NODAL AREA OF LONGITUDINAL VIBRATION OF SAID TRANSFORMER AND OPERATIVE TO INCREASE THE AMPLITUDE OF VIBRATION DELIVERED TO THE BLADE SECTION OF THE KNIFE, A RESILIENT SEALING ELEMENT LOCATED BETWEEN THE TRANSFORMER AND TUBULAR HANDPIECE AT THE APPROXIMATE NODAL AREA OF THE TRANSFORMER AND WHICH PROVIDES SUBSTANTIALLY THE SOLE DIRECT CONTACT SUPPORT FOR THE MAGNETOSTRICTIVE VIBRATOR, IMPEDANCE TRANSFORMER AND CUTTING KNIFE, A SEALING PLUG EXTENDING INTO SAID TUBULAR HANDPIECE AND SPACED FROM THE FREE END OF SAID MAGNETOSTRICTIVE VIBRATOR MEMBER AND FORMING WITH SAID SEALING ELEMENT COOLING CHAMBER THEREBETWEEN, BIAS CURRENT CONDUCTORS EXTENDING THROUGH SAID SEALING PLUG AND CONNECTED TO SAID WINDING, AND INLET AND OUTLET TUBES EXTENDING THROUGH SAID SEALING PLUG FOR SUPPLYING A COOLANT TO SAID CHAMBER AND WITHDRAWING COOLANT THEREFROM. 